Removable blade drag bits



April 22, 1958 H. J. HAWTHdRNE REMOVABLE BLADE DRAG BITS Original Filed Nov. 30, 1949 5 Sheets-Sheet l 111/ m. 5 6 W \\\\\VV mm Mm M uhwmmmm April 22, 1958 H. J. HAWTHORNE REMOVABLE BLADE DRAG BITS 5 Shets-Sheet 2 Original Filed Nov. 30, 1949 nvvrvrons Herb J. Hawthwne ATTORNEVS April 22, 1958 H. J. HAWTHORNE REMOVABLE BLADE DRAG BITS Original Filed Nov. 30, 1949 3 Sheets-Sheet 3 INVENTORS Herb .1 Hawthorne ATTORNEYS United States Patent 0.

REMOVABLE BLADE DRAG BITS Herbert J. Hawthorne, Houston, Tex.

Original application November 30, 1949, Serial No. 130,191. Divided and this application October 19, 195 Serial No. 463,202

3 Claims. (Cl. 255-61) The invention relates to the construction of a drag bit whereby removable blades may be firmly and rigidly attached to the bit body and maintained in such position until the cutter blades have been worn out.

This application is a division of copending application of Herbert 1. Hawthorne et al. of the same title, filed November 30, 1949, Serial No. 130,191, now abandoned.

The limitations of size and adaptability to the purpose to which they would be put in actual use have always caused drag bits to be discarded as impractical. Failure has come from mechanical weakness, manufacturing difliculties, or simply failure to understand the problems of drilling.

Those who more closely approached success in the development of a replaceable blade bit in the past were unable to provide any means to drill a wide variety of formations, from soft shales to reasonably hard limestone. The harder formations, and even dense shale, caused such vibration and chattering of the bit that if it did not fail by breakage, then the parts were distorted to such an extent that they could not be further used without great cost of repair. These costs were such that no savings could be made either in the manufacture or in providing economies to the user. Consequently the result was to revert back to the integral type of blade bit or to the welded-in blade drag bit.

The use of a drag bit in drilling harder formations is conducive to chattering of the bit upon the formation, and when a bit is subject to this vibration it will suffer high mechanical stresses that break the parts and cause high stresses that eventually cause failure by fatigue; and it will wear the parts to such an extent that failure will result or it will cause the parts to be distorted so as to become loose, with resultant failure. The present invention provides structure to firmly clamp removable blades to a bit body so as to provide a continuously tightening action whereby the removable blades are constantly urged into a tightly wedged position on the'bit body.

The primary object of the invention claimed in this divisional application is to provide an arrangement of interfitting and contacting parts whereby the bit body may receive the shanks of the several bit segments so that they may be laid thereon and firmly clamped in position by an overlying slidable clamping collar which is urged into wedging position to maintain the bit shanks upon the bit body. The wedging may be by the drive of the drill pipe which imparts rotation to the bit.

Other and further objects of the invention will be readily apparent when the following description is considered inconnection with the accompanying drawings, wherein:

Figure 1 is a bottom plan view looking at a bit which shows underlying features of the invention;

Fig. 2 is a sectional view taken along the drill bit assembly and illustrating the arrangement of the replaceable blades, the bit body, the clamping collar, the adapter sub, and the drill pipe;

2,831,657 Patented Apr. 22,1958.

Figures 3 and 4 are sections taken on the line 3-3 and on the line 4-4, respectively, of Fig. 2;

Fig. 5 is a transverse view along the axis of a modified form of the bit of Fig. 2 with certain of the parts broken away to illustrate the arrangement of the blades, the bit body, the clamping collar, the adapter sub, and the wing reamers as connected to the drill pipe;

Fig. 6 is a bottom plan view looking at the bit 0 Fig. 5;

Fig. 7 is a transverse section of Fig.5 taken across the interfitting and interlocking portions of the bit;

Fig. 8 is a broken detailed view of the bit body and the adapter reamer collar where the wing reamers are made integral with such collar; i

"ice

Fig. 9 is a longitudinal section showing an illustrative.

example of a bit including blade shanks, bit body, clamp. ing collar, and interfitting lugs and holes between the shanks and bit body reamer blades;

Fig. 10 is a bottom plan view looking up at the bit of Fig. 9;

Fig. 11 is a transverse section taken along the line 1111 of Fig. 9;

Fig. 12 is an enlarged elevational view of one of the cutter blades illustrating the arrangement of the cutter portion and the shank thereof.

The present invention relates generally to same subject matter as that disclosed in applicants Patents Nos.' 2,615,684 and 2,666,622.

With reference to Figures 1 and 2, the general arrange-v ment of structure will be observed. As seen in Fig. 1, there has been provided a plurality of drag blades 2; three of these blades have been shown but it is to be understood that either two-way, four-way, or other mul.-. tiple of the number of blades may be provided.

As seen in Fig. 2, these blades have a substantially central bottom cutting edge 4, and the stepped-up cutting edge 5, each of such cutting edges having a reaming edge 6. Each of these blades may have a back-up brace as shown at 7, which serves to support the cutting blade as it rotates in order to cut the earth formation.

Each of these blades is a segment of a circle, and together they comprise the composite blade 10, each blade 2 having the cutting edges 4 and 5 thereon, and each blade 2 has a rounded portion 11, which extends upwardly at 12 and has the outer edge of the wing cutter.

13 merging therewith. Above the wing cutter 13 there has been provided a shank 15. The cross-section of this Figures 3 and 4 are sections taken on the lines 3'3- and 44 of Fig. 2, and Fig. 3 shows the transverse sec tion through the cutter blade just below the shank portion, and shows the curved configuration of the blade portion 10, with the thickened area 16 forming the initial portion of the shank. c

The edges of these portions, at 18 and 19, are arranged to abut complementary portions on the adjacent blades so that the cross-sectional area of the three shank portions when taken as a whole constitute a complete circle, as seen in Figs. 3 and 4.

The shanks 15 are thickened, as seen in Fig. 4, and arranged to have a curved inner peripheral surface 15a, which are arranged to lie in close contact against the surf face 20 of the bit body 21. v 1

The bit body has a passage 22 thercthrough for flushing fluid, which will pass through the composite passageway 24, best seen in Fig. 1, where the three composite blade portions provide a central opening which is par tially covered by the inner edges 25 of the lower cutter blades 4. i

Particular attention is directed to the shoulder'27 on' the inside periphery of the shank 15, because it is ary ranged to abut upon a complementary shoulder 28 provided as outstanding on the bit shank 21. In this manner when the three shanks of the cutter blades are laid upon the bit body, the shoulders 27 and 28 will engage each other, as seen in Fig. 2; so it might be said that the bit blades are hanging upon this shoulder.

The bit body 21 has a cylindrical portion 30 against which the inner periphery of the shanks are laid, and above this cylindrical portion the bit body is formed with a coarse thread 32, which is seen in Fig. 2 as receiving an adapter sub 35, into which the bit body has been shown as threaded at 36. This adapter sub may or may not have the radially extending reamer wings 38 thereon so as to maintain the size of the hole which is being drilled by the bit or to stabilize the drilling action of the blades for maintaining a straight hole. These wings also serve to clean the walls of the hole of cuttings and to smooth off ragged projections protruding into the hole.

One of the essential features of the invention is the clamping collar 40, which is slidably arranged upon the bit body 21 and has the upper cylindrical portion 41 and the lower internally tapered portion 42. This tapered portion 42 is arranged to abut against the complementary tapered portion 43 which constitutes the outer surface of the composite cylinder formed by the shanks 15 of the three bit blades.

As will be apparent from Fig. 2 this collar is slipped down over the bit body until the tapers 42 and 43 come into engagement with each other so that the collar serves to center the shanks of all of the bits and to clamp them firmly in position.

This clamping collar 40 has a square upper end or shoulder 45 which is arranged to abut the square shoulder on the lower end 46 of the adapter sub 35. In this manner it will be apparent that there will be a constant driving action by the adapter sub 35 against the clamping collar 40.

This driving action is obtained due to the rotation of the drill stem 50, which extends to the surface. This drill stem has a lower threaded pin end 51, which is received in the female thread or box members 52 in the upper end of the sub 35. The abutting shoulders 53 on the drill pipe and the adapter sub act as the driving surface.

As is usual, the drill pipe is rotated in a clockwise direction, which will tend to make up the thread 51, which is usually a right-hand thread. This imparts a right-hand or clockwise rotation to the adapter sub 35 so that it makes up or screws onto the upper end of the bit body 20.

Thus it is apparent that once the replaceable blades are arranged about the bit body 20 and the clamping collar 40 dropped into position, that then the shanks are firmly held against the bit body due to the wedging action of the co-operating tapered surfaces 42 and 43.

Beyond cylindrical surface 30 of the bit body is a noncylindrical portion which in the embodiment of Figures 14 is characterized by fiat portions 60, three of which are best seen in Fig. 3. These flats are arranged to cooperate with a complementary flat surface 61 on the inside of the shank 15. With this arrangement the shanks are firmly held against rotational movement by the flat area held against vertical movement downwardly by the co-operating shoulders 27 and 28, and they are firmly held against upward movement by the co-operating tapered surfaces 42 and 43 on the clamping collar and the outer periphery of the shanks.

It is believed that with the foregoing construction it Will be apparent that the blades are firmly locked in position, and in event of hard digging and chattering of the bit the parts are so firmly held together that the blades and the body act as an integral member and the blades do not become loosened, distorted, nor misplaced.

The engagement of the adapter sub thread 36 to bit body thread 32 and the sub against the shank conducts the drive and thrust from the bit shank directly to drill pipe.

Figs. 5, 6 and 7 show a slightly modified form of construction where the drill pipe 50 is threaded onto the upper end of the bit body 21 and has its lower end 71 bearing against a shoulder 72 of an internal flange 73 which is arranged in the reamer body 74. This reamer body has an internal tapered surface 75 which is arranged to abut the tapered surface 76 on the clamping collar 40 which is of somewhat the same construction as the locking collar of Fig. 2.

It will be apparent therefore that the rotative drive of the drill pipe 50 is imparted to the flange on this locking collar which in turn holds the bit blade 80 in position.

The lower end 81 of the bit body is modified somewhat in that it has longitudinal flutes or grooves 82 which are formed in the normal circumferential surface. In transverse section these flutes or grooves appear as notches 84 as seen in Fig. 7 so that they form a driving shoulder 85 to receive the thickened portion 86 of the shank of the bit.

, The curved inner peripheral surface 83 of each of the blades is provided with a transverse lug 88 which engages in the annular groove 87 on the end 81 of the bit body 21.

Particular attention is directed to Figs. 5 and 6 which show an arrangement of the finger cutting blades where a plurality of fingers 89 which are substantially triangular in cross section are shown as having been radially arranged along the blades. The central fingers 90 are the longest, the intermediate fingers are at 91, and the shortest reaming fingers are shown at 92. The liquid or drilling mud which is circulated down through the drill stem and out the bit will discharge from the opening 24 formed between the several bit blades when they are assembled together.

The radial spacing of the fingers provides the space 93 with the fingers tracking to drill harder formation while the web 94 between the fingers serves to cut away additional formation which may remain after the fingers have travelled around the formation. The fingers may, however, be non-tracking to more etficiently drill softer formation.

Fig. 8 shows a slightly modified form of the bit body 21 where a tapered pin body 96 has been arranged to be received in the usual form of tapered box member on the lower end of the drill pipe or drill collar.

Figs. 9, 10, 11, and 12 illustrate a still further arrangement of the retaining mechanism wherein the bit body 100 has a cylindrical surface with the outstanding lugs 101 thereon, which are seen as cylindrical in Fig. 11. These lugs are arranged to fit into the half-holes 102, which are formed in the blade shank 103. These blade shanks have an arcuate inner surface to lie upon and against the periphery of the bit body 100. The blades are assembled on the bit body so that the half-holes 102 form about the lugs 101, as best shown in Figure 11. The counterclockwise edges (as shown in Fig. 11) of shanks 103 are designated by reference characters 18. The clockwise edges are designated by reference characters 19' (see analogous designation of shank edges 18 and 19 in Fig. 3).

The outer surface of the shank 103 is tapered so as to form a mating surface with the inner periphery 104 of the clamping collar 105, which is slidable along the bit body 100 until it clamps in position, best seen in Fig. 10.

In order to wedge the clamping bowl 105 on the shanks of the bits an adapter sub 106 is shown as having been threaded onto the upper end 107 of the bit body so that the lower end 108 of such adapter will abut against the upper end of the clamping collar and force it into wedging position to retain the bits in proper position.

The drill stem 50 is threaded at 109 and has a tapered shoulder 110 to abut against the upper taperedsur'face 111 on the adapter sub. In this arrangement the rotative drive of the drill pipe will serve to tighten the drill pipe in the adapter sub. The adapter sub is in turn threaded onto the bit body, and in turn drives the locking collar into wedging action to hold the bit blades-in place.

This form of the invention shown in Figs. 9-12 is some what similar to Figs. 2 and 5.

The blade 103 is modified somewhat in that it has discharge openings 114 in addition to the central opening for the discharge of flushing fluid, and in this manner a stream of fluid will wash the cutter blades clear of any cuttings.

All of the various structures above described embody the general principles disclosed in the prior co-pending applications hereinbefore mentioned and provide a structure by which the bit blades may be securely held in position in spite of the tremendous vibrations which are set up in the metal due to the chattering of the bit upon the formation during the rotary method of drilling.

It will be borne in mind that in many drilling operations twenty thousand to thirty thousand pounds of weight are placed upon the drill bit, and it may be rotated at several hundred revolutions per minute, so that it is easy to see that a tremendous stress will be applied to the bit blades and to the structure by which these blades are held in position.

One of the most important functions of the structure is the axial clamping action which has been illustrated as assuming any one of several forms. It is believed that a simple and economical connection has been devised wherein the thrust can be resisted and the blades held in position under tremendous stresses. The arrangement of the interfitting shoulders in combination with the tapered wedging action of the clamping collar or bowl results in rigid positioning of the blades.

The several bit blades are locked against rotational movement with respect to the bit body in most instances by the arrangement of a positive shoulder or notch-engagement drive, but in some instances the tremendous friction set up between the parts serves to hold the blades against any rotative movement.

In some instances flat areas are provided upon the bit body and the internal surface of the shanks so that these flats will fit together and when clamped in position are substantially immovable one with respect to the other.

Various modifications of structure have been illustrated for aflixing the reamer blades in position, and while the reamer wing blades have been shown as integral with the adapter sub in some instances, it is to be understood that they may be made separate and affixed in position in any desired manner.

The axial blade location relative to the bit shank is accomplished by the straight cylindrical engagement between the inner surface of the blades and the shank and the outer surface of the bit shank so as to locate the cutting or reaming edge of the several blades relative to the axial center of the assembly. This position is fixed by means of the clamping action of the adapter sub, and is independent of the manner by which the blades are locked against downward movement.

The blade-positioning relative to each other is effected by locating the blades evenly one with respect to the other by an interlocking arrangement, shown in the drawings, due to the recess and lug construction, which causes the blades to maintain their same relative axial position.

The arrangement of the removable blades provides for the passage of the drilling fluid from within the drill pipe through the bit and out into the Well bore over the cutting faces of the blades in order that the cuttings may be washed away from the bit.

Each blade is made with a recess on its axial face, which, by engaging the axial cutting face of an adjacent blade, forms a fluid port. Thus the eroding or cutting action of the circulating fluid is confined to the removable These fluid ports may be faced with abrasive-resistant material or not, as desired. In some of the forms of larger bits it may be desirable to locate the fluid ports in a different position than described 'so as to realize a more beneficial effect from the jetting action of the drilling fluid as it is directed from the fluid ports into the forma: tion being drilled, in which case the fluid ports would be made in much the same manner as are those inthe con-. ventional drag bits, by being located in the removable blade.

Broadly the invention contemplates a detachable blade bit assembly whereby the blades may be firmly clamped in position and readily removed at field locations, and wherein the forged type of replaceable blade bits are of uniform workmanship and materials so that all of the bits are interchangeable one with the other and so that, also, a uniform result may be obtained and parts stocked at any field or warehouse location to be applied to any bit without difficulty.

Certain unclaimed features described herein are claimed in copending applications of Hawthorne et al., Serial No. 601,014, filed July 30, 1956, and Serial No. 611,942, filed September 25, 1956.

Various modifications of the invention will occur to others upon reading this disclosure. Therefore,'it is in tended that the scope of the present invention be not limited to the hereinabove detailed description, but only by the appended claims.

What is claimed is:

1. A rotary drill bit comprising a bit support member having a downwardly extending portion annular in crosssection, a plurality of cutter body members surrounding said bit support member, each of said cutter body members having an arcuate inner face and an outside surface which extends downwardly and outwardly over said portion of the bit support member, a cutter blade integral with each of said body members and projecting downwardly therefrom, pins, and holes receiving said pins, on and in said cutter body members and bit support member, for interlocking said cutter body members and bit support member against the tendency of said cutter blades to retrogress in a rotational sense on said bit support member or move axially of said bit support member under the rotary section, a plurality of cutter body members surrounding I said bit support member, each of said cutter body members having an arcuate inner face and an outside surface which extends downwardly and outwardly over said portion of the bit support member, a cutter blade integral with each of said body members and projecting downwardly therefrom, pins, and holes receiving said pins, along each of said cutter body members and said bit support member for positively aligning said cutter bodymembers and bit support member with respect to each other and interlocking the same against the tendency of said cutter blades to retrogress in a rotational sense on said bit support member or move axially of said bit support member under the rotary and axial forces of drilling, sleeve means having a tapered inside extending downwardly and outwardly over the outsides of said cutter body members for restraining said cutter body members to said bit support member against escape from the interlocked positions, and means connected to said bit support member for longitudinally thrusting said sleeve to the restraining position.-

3. A detachable blade bit comprising a plurality of blades each having a shank, a body having a blade shank receivingportion generally circular in cross-section, a portion of each bl-ade shank being fitted to engage said shank receiving portion of the body over an extended area, inter-engaging means between the body and shanks to prevent relative rotation therebetween, and a clamping collar forced over the shanks to directly engage the shanks to maintain same in clamped relationship on the body, the inter-engaging means comprising transverse lug means extending from the body, and wherein the shanks are provided with apertures for receiving the lugs, the apeh tures. being, formed one-half in the adjoining edges of each of two blade shanks.

References Cited in the file of this patent Herb 1. Hawthorne, Inc. Bulletin 47-1, dated September 1946, page 2. 

